When an employee is hired into Successfactors system, an unique user ID is created and assigned to that employee.
The business requirement is to modify the user ID assigned to the already active employee.
Successfactors uses person ID / legal entity as primary keys in most of its database.
So basically all the data maintained in the system is linked to these IDs. We cannot change/modify the person ID in edit mode as we do for most other data.
If you would like to have the employee with different person ID then it is recommended you take a dump of employee information.
i.e. all personal, job info and others and terminate previous ID.
You can then hire with desired person ID (you can do hire via import too) and all available details to create the employee data again.
This would be similar as if you are adding another user but will have all the data same as old one. This is the only safe and recommended way this requirement could be achieved.
Employee_User_ID , KBA , LOD-SF-EC-EDP , Employee Data Imports , LOD-SF-EC , Employee Central , How To